The present invention relates to an aircraft pylon noise control system, and more specifically, to an active aircraft pylon noise control system capable of reducing the overall noise of an aircraft by reducing noise associated with jet-flap interaction where the engine exhaust flow interacts with a trailing edge device (e.g., flaps or ailerons) or by redistributing noise sources and reducing jet source noise or by enhancing acoustic shielding of jet noise by an airframe surface of the aircraft.
FIGS. 1 and 2 illustrate a conventional aircraft and an aircraft wing of the aircraft, respectively. As shown in FIG. 1, the aircraft 100 includes a fuselage 101, wings 102, and a propulsion engine system 103. The propulsion engine system 103 includes engines 106 at a lower surface of the wings 102. Each engine 106 is housed in a nacelle 104 having an inlet 105 and a nozzle system 150 attached to the wing 102 via a pylon structure 108. FIG. 2 shows high-lift devices included on the wing 102. The high lift devices may include deployable slats 111 positioned toward a leading edge of the wing 102 and multiple trailing edge devices positioned toward a trailing edge of the wing 102. The trailing edge devices include an outboard aileron 113, an outboard flap 105, an inboard aileron 117, and an inboard flap 119. The outboard and inboard ailerons 113 and 117 are typically used for roll control of the aircraft 100 while the outboard and inboard flaps 105 and 119 are used to control the lift of the aircraft 100 during takeoff and landing operations. The ailerons 113 and 117 are hinged devices that are un-gapped when in their deployed position. When the flaps 105 and 119 are deployed, they rotate and move in an aft direction to open a gap relative to the wing 102 (as depicted by arrows 121 and 123). Since the motion path of the inboard flap 119 (as indicated by arrow 121) converges with the motion path of the outboard flap 105, the inboard aileron 117 located between the flaps 105 and 119 may be a hinged device and does not move aft when deployed (as indicated by arrow 125). When a flaperon is used in place of the inboard aileron 117, it moves in an aft direction unlike the inboard aileron 117.
Aircraft noise continues to have a significant negative impact on the environment, e.g., on the air transportation system and the public. There are several factors that contribute to overall aircraft noise. These factors include the different operations (e.g., takeoff, approach, and cruise) of the aircraft 100. The level of noise may vary depending on the operation. For example, jet noise is typically higher during a takeoff operation. Further, shock cell noise may occur during a cruising operation of the aircraft 100 which may affect the passengers and crew aboard the aircraft 100. In addition, the interaction of the engine jet exhaust with a deployed high-lift device (e.g., flaps 105 and 119, or ailerons 113 and 117) is another source of noise and is accentuated based upon a configuration of the propulsion engine system 103.
Therefore, it is desirable to have an aircraft pylon noise control system capable of reducing jet-flap interaction noise and redistributing noise sources within the aircraft to enhance acoustic shielding by the aircraft.